Composition and ecology of bacterial and archaeal communities in anaerobic reactor fed with residual glycerol

Abstract

Glycerol, the main residue of biodiesel production, can be used to produce organic acids and energy through anaerobic digestion. This study aimed to assess microbial structure, diversity, productivity, and stability and the influence of these parameters on the performance of an anaerobic reactor. The exper- imental setup consisted of an upflow anaerobic sludge blanket (UASB) reactor fed residual glycerol and nutrients. The organic loading rate (OLR) was gradually increased through five stages, and sludge samples were collected at each, followed by DNA extraction and PCR denaturing gradient gel electro- phoresis (PCR-DGGE). The resulting bands were excised, amplified, and purified. The results showed increased bacterial diversity and richness from the inoculum (Rr 38.72 and H 2.32) and along stages I and II, reaching the highest populational parameters (Rr 194.06 and H 3.32). The following stages promote decreases in richness and diversity, achieving the lowest populational parameters on this study (Rr 11.53 and H 2.04). Biogas production increased along with functional organization due to the specialization of the bacterial community and a decrease in the methanogenic population, both promoted by the increase in OLR.